The present invention is related to gas turbine engines, and in particular to a system for positioning variable vanes of gas turbine engines.
Gas turbine engines rely on rotating and stationary components to effectively and efficiently control the flow of air through the engine. Rotating components include rotor blades employed in compressor and turbine sections for compressing air and extracting energy from air after combustion. Stationary components include vanes placed in the airflow to aid in directing the airflow. By varying the orientation of the vanes (i.e., pivoting them to vary the profile provided to the airflow), airflow characteristics can be optimized for various operating conditions.
One system for providing actuation of the vanes is an actuator connected to the plurality of variable vanes via a series of linkages including synchronizing rings and vane arms. Current vane arm and synchronizing ring designs create a bending and twisting moment on the vane arm when the synchronizing ring rotates to vary the orientation of the vanes. This loading condition is caused by over constraint between a vane arm pin and a bushing in which the pin is disposed. This over constrained loading condition occurs on multiple vanes in multiple stages, and creates a large reaction load against movement of the synchronizing ring. Thus, the actuator is required to work harder to overcome the reaction load. Additionally, the loading condition also contributes to inaccuracy with regard to the orienting of the variable vanes, which has a negative impact on engine performance.